<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>

    <link rel="stylesheet" href="css/bootstrap.min.css">
    <script src="js/jquery-3.4.1.min.js"></script>
    <script src="js/bootstrap.bundle.min.js"></script>
    <script src="js/bootstrap.min.js"></script>

    <style>
        div {
            border: 1px solid;
        }
    </style>

</head>

<body>
    <div class="container">
        <div class="row">
            <div class="col-1">1</div>
            <div class="col-1">2</div>
            <div class="col-1">3</div>
            <div class="col-1">4</div>
            <div class="col-1">5</div>
            <div class="col-1">6</div>
            <div class="col-1">7</div>
            <div class="col-1">8</div>
            <div class="col-1">9</div>
            <div class="col-1">10</div>
            <div class="col-1">11</div>
            <div class="col-1">12</div>
        </div>

        <div class="row">
            <div class="col-5">5</div>
            <div class="col-5">5</div>
            <div class="col-2">2</div>

        </div>
        <!-- 
            第一行：4个格子
            第二行：8个格子
            第三行：6个格子
            多出来的6个格子跑到第二行去了
         -->
        <div class="row">
            <div class="col-4">4</div>
            <div class="col-9">8</div>
            <div class="col-2">6</div>
        </div>
    </div>
    <span>-----------</span>
    <div class="container">
          <!-- 
            嵌套布局
         -->
         <div class="row">
             <div class="col-4">4</div>
             <div class="col-8">
                 <!-- 对于8个格子，还可以划分为12份 -->
                 <div class="row">
                     <div class="col-3">3</div>
                     <div class="col-9">9</div>
                 </div>
             </div>
         </div>
    </div>

    <div class="container">
        <div class="row">
            <div class="col-4">4</div>
            <div class="col-8">
                <div class="row">
                        <div class="col-1">1</div>
                        <div class="col-1">2</div>
                        <div class="col-1">3</div>
                        <div class="col-1">4</div>
                        <div class="col-1">5</div>
                        <div class="col-1">6</div>
                        <div class="col-1">7</div>
                        <div class="col-1">8</div>
                        <div class="col-1">9</div>
                        <div class="col-1">10</div>
                        <div class="col-1">11</div>
                        <div class="col-1">12</div>
                </div>
            </div>
        </div>
    </div>

</body>

</html>